Along with the recent size reduction of semiconductor devices, various kinds of lithography means for exposure on the order of 100 nm or less have been proposed. There are also requirements for high resolution, accurate lithography pattern overlay, and high throughput. Electron beam exposure apparatuses inherently ensure a high resolution and also have satisfactory dimension controllability as compared to other exposure means. Since the electron beam exposure apparatuses can electrically generate an exposure pattern and directly expose a wafer, they are expected as maskless exposure means.
In the electron beam exposure apparatuses, however, the exposure area per shot is small, and the throughput is low. For these reasons, they are not widely used for mass production of semiconductor devices. To solve these problems, a multi-electron beam exposure apparatus which exposes a wafer by using a plurality of electron beams simultaneously has been proposed.
Such a multi-electron beam exposure apparatus comprises a blanking aperture array device which switches a plurality of electron beams between an independent deflection mode and another mode, and an electron beam shielding section which shields the wafer from the electron beams deflected by the blanking aperture array device. With these units, whether the wafer is to be irradiated with each of the plurality of electron beams is accurately controlled. The blanking aperture array device has a substrate such as a semiconductor substrate having a plurality of openings (also called through holes), deflection electrodes formed in the openings, and an insulating layer which insulates the substrate from the deflection electrodes. Whether an electron beam that passes through an opening is to be deflected is controlled by ON/OFF-controlling voltage application to the deflection electrode.
In the conventional blanking aperture array device manufacturing process, openings each having a high aspect ratio are formed in a substrate. A deflection electrode is formed in each of the openings by plating. Since the deflection electrode is formed by plating in the opening having a high aspect ratio, a material whose plating growth rate is low cannot be selected as the material of the deflection electrode. In addition, if the deflection electrode is oxidized, it becomes difficult to appropriately deflect an electron beam and control its position. To prevent this, a material that is hard to oxidize must be selected as the material of the deflection electrode. It is difficult to select the deflection electrode material that meets the above requirements.
In the conventional structure of the blanking aperture array device, the substrate or insulating layer is partially exposed to the inner wall of each opening through which an electron beam passes. For this reason, the oxide film of the substrate or the insulating layer, which is exposed to the inner wall of the opening, is charged up and affects the electron beam that passes through the opening. Accordingly, the electron beam cannot be appropriately deflected or position-controlled. Hence, it is difficult to accurately expose the wafer.
In the conventional blanking aperture array device manufacturing process, openings are formed in a substrate, and an insulating layer is formed on the inner wall of each opening. At a position adjacent to the insulating layer, a deflection electrode is formed by plating using a conductive layer formed on the surface of the substrate as an electrode. The deflection electrode has residual stress and therefore poor adhesion to the insulating layer. For this reason, the deflection electrode readily peels off from the insulating layer.
Under these circumstances, a deflector, a method of manufacturing the same, and a charged particle beam exposure apparatus, which can solve the above problems, are demanded.